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How To Specify Limited Number Of

Connections In your Server

Most applications serving downloading from internet like

IDM and DAP tries to setup parallel or simultaneous

connections to a download server in order to gain faster

download speed. However with the multiplication in the

number of parallel connections for faster download can even

take the server down. So you can say that as the number of

parallel connection increases the download speed from the

server decreases. Here in this article the word server is stands

for Dedicated Server or Virtual Private Server (VPS)

Here we will guide you on how you can set a boundary for

total number of connections coming from a single IP towards

your server to avoid traffic. This will limit the number of

connections and prevent the server from getting down. This

will be of great help while RapidLeech transloading server or

building file sharing site. To speed up the loading speed, most

of the latest web browsers set compound connection. This

makes setting the number of connection for a single IP the

best option for your server. Although defining a limited

number of connections does not mean to set connection limit

to one for your website. This will make the website guest

think that the traffic is too low at your site and it may take

more than a while for data loading. One should set a limit

which should not as low as one or not as high as hundred.

Though the total number of parallel connection on the server

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is up to the Admin however 20 is the better number for you to

move on with. Like this you can set the maximum number of

simultaneous connection on a server for a single IP by using

port 80 which is a default http port.

Here we have used Ubuntu-based server, however other

Distros will not exactly be same but can be consider similar.

Steps on how to limit maximum connections in your server

Step 1:You need to login to your server via SSH and for that

we will be using PuTTY to connect to your dedicated server

or VPS.

You will the below details in hand before you open PuTTY

Host:Host can be anything amongst your domain name, your

servers IP address or the name of your server eg

vps####.websitename.com

Username:Use the cPanel Username of your website

Password:Use the cPanel Password of your website

Connecting to PuTTY

a. Open PuTTY

b. Enter the Hostname

c. Click Open

d. Click YES if you get PuTTY security alert

e. Login As message will appear on the screen.

f. Enter Username. Click Enter

g. Enter Password. Click Enter

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When you have successfully logged in you will see

username@vps####.websitename.com [~]#.

Step 2: Inter following commands to iptables rule in order torestrict connections to N number. Where N will be the number

of connections you want to keep connected at a time.

The default command syntax for Firewall configuration is:

iptables A INPUT p tcp syn dport $port

m connlimit connlimitabove N j REJECT

rejectwith tcpreset

Change $ port with the port number you wish to limit the

connection. Make it 22 for SSH and for http change it to 18.

Eg: In order to limit the connection to 20 write the following

commands.

iptables A INPUT p tcp syn dport 80 m

connlimit connlimitabove 20 j REJECT

rejectwith tcpreset

Example for the command:

The above command will limit the permitted SSH to 3 forsingle IP.

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iptables A INPUT p tcp syn dport 22 m

connlimit connlimitabove 3 j REJECT

And follow this syntax for RedHat and friends:

/sbin/iptables-A INPUT -p tcp --syn --

dport 80 -m connlimit --connlimit-above

20 -j REJECT --reject-with tcp-reset

Step 3:Once done with the commands you further need to

save that configuration. So that RedHat and friends can use it:

Follow the below mentioned command

service iptables save

you can even save the currently active iptables rule using the

below mentioned command syntax (Ubuntu, Debian and

friends):

iptables-save > /etc/iptables.up.rules

You can see the plan in action same as the given screenshot:

Step 4: The above explained steps will only make iptables

rules gets flushed of every time you will reboot the server.

Thus you will also need to follow the below command as well.

Firstly you need to create a new file which will be called

every time the network interface will get enabled. Below you

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will find the command for creating that file and screenshot for

the same.

nano /etc/network/if-pre-up.d/iptables

Screenshoot:

Step 5: Once done with the launching of nano editor now its

time to reload the iptables rules. And for that you need to

write these commands:

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#!/bin/bash/sbin/iptables-restore